In such technologies, a technology described in, for example, Patent Document 1 is known. The invention described in Patent Document 1 includes a maintenance device for managing an input signal from an encoder, a control signal to a servo motor, a control signal from a high-order control device, and an internal signal of a servo amplifier in the process of generating the control signal to the servo motor, which are collected in a constant cycle. The maintenance device carries out abnormality monitoring of the servo amplifier, and concurrently outputs an operation parameter to the servo amplifier, controls an operation of the servo amplifier, and allows the servo amplifier to collect predetermined signals. The maintenance device displays, for example, a change of the collected information in a line chart based on the collected information. Then, the maintenance device stops collecting information about the servo amplifier when the received collected information satisfies the preset stop condition.
However, according to the invention described in Patent Document 1, data to be collected must be set in advance. Therefore, when data to be extracted are changed, selection itself of necessary data is required to be changed. In particular, in controlling a motor, various evaluation indices for quantitatively evaluating control characteristics of a motor control system have been proposed. When an evaluation value based on such evaluation indices is intended to be calculated, a different calculation method for each evaluation index is necessary. In addition, data corresponding to the calculation method are required to be selected in measurement. Therefore, when an evaluation index is changed, an operator is required to have knowledge and skill to select data necessary for calculation of the evaluation value.
[Patent Document 1] Japanese Patent Unexamined Publication No. 2001-75637